# Characterization of Ti/Cu Dissimilar Metal Butt-Welded by the Cold Welding Process

## TL;DR

This paper explores using cold welding to join titanium and copper, achieving strong joints with minimal brittle compounds.

## Contribution

A novel cold welding method is proposed for Ti/Cu dissimilar metal welding, achieving high joint strength with reduced brittle intermetallics.

## Key findings

- The weld fusion zone mainly consists of Cu-based solid solution and Cu3Ti.
- Low heat input in cold welding reduces Cu3Ti content, preserving joint mechanical properties.
- The joint achieves 284 MPa tensile strength and 6.25% elongation rate.

## Abstract

Titanium alloys and copper have broad applications in aerospace, defense, and industry, but their dissimilar welding faces challenges from significant physicochemical differences and easy formation of brittle Ti-Cu intermetallic compounds, while existing methods like laser welding or friction stir welding have limitations, such as low strength or inability to weld ultra-thin plates. This study adopted cold welding to join Ti-6.5Al-1Mo-1V-2Zr alloy and 99.90% pure copper. The mechanical properties of the joint were tested, the microstructure and fracture of the weld were observed, and the phase composition of the weld was analyzed. The results show that the weld fusion zone mainly consists of Cu-based solid solution and Cu3Ti. Low cold welding heat input reduces the Cu3Ti content, so the joint mechanical properties do not decrease significantly. The tensile strength of the joint reaches 284 MPa, which is 83% of that of copper-based metals, and the elongation rate reaches 6.25%. Diffusion kinetics and solidification thermodynamics analyses confirm that Cu3Ti intermetallic compounds are preferentially generated in the weld seam.